NAME

       FBB::SharedMutex - Mutex for shared memory

SYNOPSIS

       #include <bobcat/sharedmutex>
       Linking option: -lpthread, -lbobcat

DESCRIPTION

       Shared memory may be used by multiple processes. To synchronize access to shared memory an
       FBB::SharedMutex may be defined inside a shared memory segment. An FBB::SharedMutex allows
       clients  to lock a shared memory segment before reading or writing its contents. E.g., the
       Bobcat class FBB::SharedSegment defines a SharedMutex in its shared memory segment.

       The FBB::SharedMutex class uses the facilities offered by the PThread library to implement
       shared  memory  locking. To force unlocking a (possibly) locked shared memory segment, its
       destructor can be called.

NAMESPACE

       FBB
       All constructors, members, operators and manipulators, mentioned  in  this  man-page,  are
       defined in the namespace FBB.

INHERITS FROM

       -

CONSTRUCTORS

       o      SharedMutex():
              The  default  constructor initializes an FBB::SharedMutex object to a shared memory
              mutex (using the PTHREAD_PROCESS_SHARED attribute). As an  FBB::SharedMutex  object
              will  normally  be  defined  inside  a shared memory segment the object’s memory is
              already available.  In  this  case  placement  new  should  be  used  to  call  the
              constructor. E.g., if a shared memory segment is attached to the current process at
              d_shared, and an FBB::SharedMutex should be defined at d_shared’s address, then the
              FBB::SharedMutex object can be initialized like this:

                  new (d_shared) FBB::SharedMutex;

              The copy and move constructors are not available.

       The  class’s destructor releasea all of the current process’s nested shared memory segment
       locks. To destroy an FBB::SharedMuted object that has been constructed using the placement
       new operator use

           d_sharedMutex->~SharedMutex();

       (assuming  SharedMutex  *d_sharedMutex  points  to  the  location  where placement new has
       previously initialized the FBB::SharedMutex object.)

MEMBER FUNCTIONS

       o      void lock() const:
              When returning from this member, the current process has locked the  shared  memory
              segment.

       o      void unlock() const:
              The object’s lock of the shared memory segment is released.

EXAMPLE

       See the sharedstream(3bobcat) man page.

FILES

       bobcat/sharedmutex - defines the class interface

SEE ALSO

       bobcat(7)     isharedstream(3bobcat),     osharedstream(3bobcat),    sharedblock(3bobcat),
       sharedmemory(3bobcat), sharedpos(3bobcat), sharedsegment(3bobcat),  sharedstream(3bobcat),
       sharedstreambuf(3bobcat)

BUGS

       None Reported.

DISTRIBUTION FILES

       o      bobcat_3.19.01-x.dsc: detached signature;

       o      bobcat_3.19.01-x.tar.gz: source archive;

       o      bobcat_3.19.01-x_i386.changes: change log;

       o      libbobcat1_3.19.01-x_*.deb: debian package holding the libraries;

       o      libbobcat1-dev_3.19.01-x_*.deb:  debian  package holding the libraries, headers and
              manual pages;

       o      http://sourceforge.net/projects/bobcat: public archive location;

BOBCAT

       Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.

COPYRIGHT

       This is free software, distributed under the terms  of  the  GNU  General  Public  License
       (GPL).

AUTHOR

       Frank B. Brokken (f.b.brokken@rug.nl).